Add deprecation warnings about types

Author: nepalez

lib/dry/initializer/plugins/type_constraint.rb

@@ -14,7 +14,7 @@ def type
     end
 
     def dry_type?
-      type.class.ancestors.map(&:name).include? "Dry::Types::Builder"
+      type.respond_to? :call
     end
 
     def plain_type?
@@ -24,6 +24,9 @@ def plain_type?
     def module_type_constraint
       return unless plain_type?
 
+      warn "[DEPRECATION] support for ruby modules as type constraint" \
+           " is deprecated. Use dry-types instead."
+
       "fail #{TypeError}.new(:#{name}, #{type}, @#{name})" \
       " unless @#{name} == Dry::Initializer::UNDEFINED ||" \
       " #{type} === @#{name}"
@@ -44,6 +47,9 @@ def dry_type_constraint
     end
 
     def object_type_constraint
+      warn "[DEPRECATION] support for case equality (===) as type constraint" \
+           " is deprecated. Use dry-types instead."
+
       ivar = :"@#{name}"
       constraint = type